package cn.ittiger.demo.retrofit;


import java.io.IOException;

import okhttp3.MediaType;
import okhttp3.RequestBody;
import okio.Buffer;
import okio.BufferedSink;
import okio.ForwardingSink;
import okio.Okio;
import okio.Sink;

/**
 * 扩展OkHttp的请求体，实现上传时的进度提示
 *
 * @param <T>
 */
public final class FileRequestBody<T> extends RequestBody {
  /**
   * 实际请求体
   */
  private RequestBody requestBody;
  /**
   * 上传回调接口
   */
  private RetrofitCallback<T> callback;
  /**
   * 包装完成的BufferedSink
   */
  private BufferedSink bufferedSink;

  public FileRequestBody(RequestBody requestBody, RetrofitCallback<T> callback) {
    super();
    this.requestBody = requestBody;
    this.callback = callback;
  }

  @Override
  public long contentLength() throws IOException {
    return requestBody.contentLength();
  }

  @Override
  public MediaType contentType() {
    return requestBody.contentType();
  }

  @Override
  public void writeTo(BufferedSink sink) throws IOException {
    if (bufferedSink == null) {
      //包装
      bufferedSink = Okio.buffer(sink(sink));
    }
    //写入
    requestBody.writeTo(bufferedSink);
    //必须调用flush，否则最后一部分数据可能不会被写入
    bufferedSink.flush();
  }

  /**
   * 写入，回调进度接口
   * @param sink Sink
   * @return Sink
   */
  private Sink sink(Sink sink) {
    return new ForwardingSink(sink) {
      //当前写入字节数
      long bytesWritten = 0L;
      //总字节长度，避免多次调用contentLength()方法
      long contentLength = 0L;

      @Override
      public void write(Buffer source, long byteCount) throws IOException {
        super.write(source, byteCount);
        if (contentLength == 0) {
          //获得contentLength的值，后续不再调用
          contentLength = contentLength();
        }
        //增加当前写入的字节数
        bytesWritten += byteCount;
        //回调
        callback.onLoading(contentLength, bytesWritten);
      }
    };
  }
}
